Last week I officially switched (reluctantly and with a bad taste in my mouth) from Spotify to Apple Music.
Why? Simply because when I'm driving I want to dictate by voice command what song I want to play. I could not do this with Spotify, that's why I switched.
Next time I won't get an iphone because of the bad taste this experience has left me (the worst part is apple's voice transcription technology is so bad compared to Google's... so half the time even that doesn't work)
Compare this with being able to play a song by simply saying "Hey Siri play Beatles' Rain"... and that is it.
Compare this with "hey Siri play bob Dylan's blowing in the wind" and it working just with this
Apple should have opened Siri to spotify.
So, I have an iphone 6s -- and I use Siri a _lot_. Mostly I use it when I'm talking to friends or family... e.g. today someone told me he didn't know any of Dylan's songs... and I went "oh, well let me tell you of some!"
Usually when you're talking to someone, and you spend half the time on your device suddenly disconnected from the person you're talking to, that makes things tough. Generally one should optimize for a friction-free experience. Generally, that means trying to do whatever in the least amount of steps.
When Apple refuses to open up siri, it makes things really difficult.
I mean really, this is from direct personal experience. My decision to quit spotify recently was literally this. (another was driving -- I need to go hands-free and least-steps there too for my own sake)